Clear delegation on deregistration

common/src/stake_addresses.rs

@@ -412,6 +412,7 @@ impl StakeAddressMap {
         if let Some(sas) = self.get_mut(stake_address) {
             if sas.registered {
                 sas.registered = false;
+                sas.delegated_spo = None;
                 true
             } else {
                 error!(

modules/accounts_state/src/rewards.rs

@@ -346,6 +346,11 @@ fn calculate_spo_rewards(
                 let reward = &to_delegators * &proportion;
                 let to_pay = reward.with_scale(0).to_u64().unwrap_or(0);
 
+                // Skip if it's rounded to zero
+                if to_pay == 0 {
+                    continue;
+                }
+
                 debug!("Reward stake {stake} -> proportion {proportion} of SPO rewards {to_delegators} -> {to_pay} to hash {}",
                        delegator_stake_address);
 

modules/accounts_state/src/state.rs

@@ -835,6 +835,7 @@ impl State {
     /// Record a stake delegation
     fn record_stake_delegation(&mut self, stake_address: &StakeAddress, spo: &PoolId) {
         let mut stake_addresses = self.stake_addresses.lock().unwrap();
+        debug!("Delegation of {} to {}", stake_address, spo);
         stake_addresses.record_stake_delegation(stake_address, spo);
     }